1. Field of the Invention
This invention relates to a magnification changeover device for a camera and more particularly to a magnification change-over device suited to a 35 mm camera, a half-size camera and a disc camera.
2. Description of the Related Art
Generally, a camera with a magnification change-over device is known as a 2-focal-point camera. The conventional 2-focal-point camera moves the barrel part of a photo-taking lens back and forth in response to a focal length changeover operation. The conventional camera of this kind, however, has the following three problems: First, since a lens barrel unit including an automatic focusing device and a shutter control device is arranged to be movable, it has been not easy to connect these devices to applicable parts or to a power source disposed inside of the camera body. Further, since these devices must be arranged to be chargeable with the lens barrel unit both in a drawn-in position and in an extended position, the camera necessitates use of expensive connectors and a complex charging device and thus results in an increased cost.
Secondly, since the lens barrel part is to be moved in and out, the camera cannot be sufficiently waterproofed. Besides, with dust or the like sticking to the side surface of the lens barrel part while it is in an extended state, the dust would be pulled into the inside of the camera when the lens barrel part is drawn in. In that event, the operation of the camera would be affected by the dust. Further, many inner and outer parts overlap each other when the lens barrel is drawn inward into a wide-angle state (hereinafter referred to as WIDE). Therefore, this results in an excessively large camera because of the arrangement extended for blocking ambient light when the lens is drawn out and for blocking the light after completion of the operation of a shutter unit arranged at an aperture.
Thirdly, the position of the lens shifts to a great extent for change-over between a telephoto state (hereinafter referred to as TELE) and WIDE. However, the lens barrel must be arranged to shift the lens position with a high degree of precision. The lens barrel, therefore, must be carried by extremely precise arrangement and parts. This requirement also results in an increase in cost and size of the camera.